An asynchronous JavaScript and extensible mark-up language (AJAX) web application uses AJAX to communicate with a server to load data or page fragments. Programming with AJAX offers benefits in the context of web application development. For example, AJAX offers site developers an additional level of innovation that may make a site easier to use for all visitors. AJAX may also be utilized to give users the sense that a web application is more responsive than a traditional web site.
However, with the use of AJAX to manipulate web page content, an issue arises with regard to providing bookmarkability of content that may be dynamic rather than static during a user session. For example, while a web page may have a single non-changing uniform resource locator (URL) stored in the web browser, the content in many AJAX web sites is asynchronously changed and replaced. Accordingly, when a user sets a bookmark, he may only be able to capture the starting URL of the web site instead of the exact content state he is currently viewing. Users therefore will want a way to bookmark a dynamic web page in a way that allows them to restore a specific content state.
One common solution is to change the hash part of the URL, since doing so does not activate any actions, such as loading a new page on the browser side. However, this approach yields yet another issue as to how a web crawler or web robot can access that URL. Even if the hash part of the URL contains all of the information needed to fetch correct data using AJAX technology, the web crawler will not be able to access it since web crawlers are not able to execute JavaScript code inside the web pages they download.